Hydraulic oil well pumping apparatus

ABSTRACT

A hydraulic oil well pumping apparatus, preferably includes a hydraulic cylinder having a rod that is movable between a upper and lower rod positions; a pumping string that extends downwardly from the rod, the string being configured to extend into an oil well for pumping oil from the well; a prime mover; a hydraulic pump that is powered by the prime mover, said pump having a compensator that regulates pump flow and pump pressure; a directional control valve that moves between open flow and closed flow positions; an accumulator in fluid communication with the pump and directional control valve; a flow line connecting the pump and the accumulator, the directional control valve being positioned in the flow line so that it can control flow between the accumulator and hydraulic cylinder; a proportioning valve; a hydraulic fluid reservoir for containing hydraulic fluid to be supplied to the hydraulic pump; a flow line that transmits hydraulic fluid from the hydraulic cylinder to the reservoir via the proportioning valve; and an electronic control system that controls movement of the rod as it moves between the upper and lower positions by controlling the control valve and the proportioning valve, wherein the control system includes an electrical signal that opens or closes the proportioning valve so that a control of rod movement is enabled when the rod changes direction at the lower position of the rod, and wherein the proportioning valve is choked to lower flow through it as the rod is descending from the upper toward the lower position.

CROSS-REFERENCE TO RELATED APPLICATIONS

Priority of U.S. Provisional Patent Application Ser. No. 61/119,160, filed 2 Dec. 2008, incorporated herein by reference, is hereby claimed.

Priority of U.S. Provisional Patent Application Ser. No. 61/024,020, filed 28 Jan. 2008, incorporated herein by reference, is hereby claimed.

U.S. Provisional Patent Application Ser. No. 60/764,481, filed 1 Feb. 2006, is incorporated herein by reference.

U.S. Provisional Patent Application Ser. No. 60/824,123, filed 31 Aug. 2006, is incorporated herein by reference.

U.S. patent application Ser. No. 11/670,239, filed 1 Feb. 2007, is incorporated herein by reference.

PCT Patent Application Serial No. PCT/US2007/061478, filed 1 Feb. 2007, is incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

REFERENCE TO A “MICROFICHE APPENDIX”

Not applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to oil well pumps and more particularly to an improved hydraulic oil well pump that is electronically controlled using limit or proximity switches to control a valving arrangement that eliminates shock or excess load from the pumping string or sucker rod during pumping, and especially when changing direction of the sucker rod at the bottom of a stroke.

2. General Background of the Invention

Several patents have issued that relate generally to the pumping of oil from an oil well. Examples of those patents are contained in the following table, wherein the order of listing has no significance other than chronological.

TABLE ISSUE DATE PATENT DOC. NO. TITLE MM-DD-YY 3,726,093 Variable displacement pump control assembly 03-02-1976 4,503,752 Hydraulic Pumping Unit 03-12-1985 4,631,918 Oil-well pumping system or the like 12-30-1986 4,761,120 Well Pumping Unit and Control System 08-02-1988 5,143,153 Rotary Oil Well Pump and Sucker Rod Lift 09-01-1992 5,390,743 Installation and Method for the Offshore 02-21-1995 Exploitation of Small Fields 6,017,198 Submersible well pumping system 01-25-2000 6,394,461 Pressure Compensated Stuffing Box for 05-28-2002 Reciprocating Pumping Units 2003/0085036 Combination Well Kick Off and Gas Lift Booster 05-08-2003 Unit 6,595,280 Submersible Well Pumping System with an 07-22-2003 Improved Hydraulically Actuated Switching Mechanism 2005/0155758 Well Tubing/Casing Vibrator Apparatus 07-21-2005

BRIEF SUMMARY OF THE INVENTION

The present invention provides a hydraulic oil well pumping apparatus. The system of the present invention utilizes a hydraulic cylinder having a piston or rod that is movable between upper and lower piston positions. A pumping string or sucker rod extends downwardly from the piston, the pumping string or sucker rod being configured to extend into an oil well for pumping oil from the well.

A prime mover such as an engine is connected to a compensating type hydraulic pump.

A directional control valve moves between open flow and closed flow positions. A hydraulic flow line connects the pump and the hydraulic cylinder.

Electronic controls are provided that control movement of the piston as it moves between the upper and lower positions.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein:

FIG. 1 is a schematic diagram of an embodiment of the apparatus of the present invention;

FIG. 2 is a schematic diagram of another embodiment of the apparatus of the present invention;

FIGS. 3-4 are elevation views of a preferred embodiment of the apparatus of the present invention showing an alternate construction for the pump cylinder, wherein lines A-A are match lines and FIG. 4 is taken along lines 4-4 of FIG. 3;

FIG. 5 is a fragmentary, sectional elevation view of a preferred embodiment of the apparatus of the present invention taken along lines 5-5 of FIG. 3;

FIG. 6 is a partial sectional elevation view of the preferred embodiment of the apparatus of the present invention and showing the alternate construction for the pump cylinder; and

FIG. 7 is a schematic diagram of another alternate embodiment of the apparatus of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an embodiment of the apparatus of the present invention, designated generally by the numeral 150. Oil well pump 150 provides a pump (e.g. hydraulic piston pump) 153 that receives hydraulic fluid via a reservoir 151 and intake flow line/filter 152. The hydraulic piston pump 153 is driven by a prime mover (e.g. engine or electric motor). A manifold assembly 154 is shown surrounded by dotted lines in FIG. 1. The manifold assembly 154 includes various flow lines as shown in FIG. 1, directional valve 165, proportional flow control valve 171, relief valve 175, and valves 174, 176. A discharge flow line 155 extends from the discharge side of pump 153 to internal manifold tee 157. Check valve 156 can be placed in discharge flow line 155. Valves 161, 171, 174, 175, 176 can be a part of (e.g. internal) manifold 154.

At internal manifold tee 157, flow lines 158, 159 communicate with discharge flow line 155. The flow line 159 extends through flow control valve 164 and to accumulator 160. The accumulator 160 has an oil containing portion 161 and a gas containing portion 162. In FIG. 1, arrow 163 indicates schematically the level of oil 161 in accumulator 160.

Hydraulic cylinder 166 is connected to both accumulator 160 and pump 153 via flow line 158. Hydraulic cylinder 166 includes a cylinder body 167 and an extendable pushrod 168. The pushrod 168 is movable between retracted upper and extended lower positions. The pushrod 168 provides a rod end 169 that is fitted with a coupling (e.g. coupling 20 of the embodiments of FIGS. 1-42 in Publication No. US 2007/0261841A1, published 15 Nov. 2007, and in Publication No. WO 2007/090193 A2, published 9 Aug. 2007, both of which are hereby incorporated by reference) which connects the pushrod 168 to a well string such as the pumping string 21 (e.g. sucker rods) shown in FIGS. 1-42 in Publication No. US 2007/0261841A1, published 15 Nov. 2007, and in Publication No. WO 2007/090193 A2, published 9 Aug. 2007. Flow line 170 extends from internal manifold tee 177 through proportional flow control valve 171 to reservoir 178. Reservoirs 151, 178 can be a common reservoir. The flow line 170 can be provided with an oil cooler 172 and filter 173. Excess pressure in the system can be relieved using relief valve 175. Valve 176 is a valve that controls flow of fan/cooler 172.

In operation, the prime mover (e.g. engine or electric motor) is started which operates hydraulic pump 153. The hydraulic pump 153 initially rotates at a speed of about 1800 rpm's and is destroked. The hydraulic pump 153 can be a Parker Model P1075XS (01SRM5AEY0T00CPB). A pumping cycle begins by giving the hydraulic piston pump 153 a command using a controller (such as the controller 39 described herein in reference to FIGS. 1-42), stroking it to charge accumulator 160. When accumulator 160 is fully charged, the directional valve 165 is energized, while maintaining the command to the pump 153. Oil 161 is then directed from the charged accumulator 160 through the flow control valve 164 and from the pump 153 into the rod end 168 of the hydraulic cylinder 166. Valve 164 enables free flow in and restricted flow out to control speed of upstroke of cylinder 166. Pushrod 168 will then retract lifting the pumping string until a proximity switch is actuated by a coupling that is mounted on the rod end 169.

The controller 39 then de-energizes the directional valve 165 and activates the proportional control valve 171 forcing it to open until the pushrod 168 begins to fall at a desired velocity. The degree of opening of the proportional control valve 171 controls how fast fluid leaves the cylinder body 167 and flows via flow lines 158, 170 through the proportional flow control valve 171 and into reservoir 178.

Eventually, the coupling on the rod end 169 reaches a second proximity switch which is positioned a short distance (e.g. approximately one foot) from the bottom of the travel of the pushrod 168. When the coupling reaches the second proximity switch, a current signal to the proportional control valve 171 is decreased, forcing the pushrod 168 to decelerate until the coupling 20 on the rod end 169 of the pushrod 168 reaches a third proximity switch. The electrical signal from the controller 39 will then be removed from the proportional control valve 171, with a voltage signal then being sent by controller 39 to the directional valve 165 while maintaining the command to the pump 153 to continue pumping. Oil 161 returning from the cylinder body 167 through the proportional control valve 171 passes through an oil cooler 172 and filter 173 before reaching reservoir 178.

During the time that the pushrod 168 is extending with respect to the cylinder body 167, oil 161 is being pumped by the pump 153 to the accumulator 160, charging the accumulator 160 for use in the next cycle. The accumulator 160 will thus have a pressure change of between about five hundred (500) psi depending on sucker rod string load when it has been discharged by transmitting fluid to the cylinder 166 and a maximum pressure value of about three thousand (3,000) psi depending on sucker rod string load when it is fully charged by the pump 153 during that time that the pushrod 168 is extending and cylinder 166 is draining.

FIG. 2 shows another embodiment of the apparatus of the present invention designated generally by the numeral 180. Oil well pump 180 is somewhat similar to the embodiment of FIG. 1, with the elimination of bypass valve 174, that function now being taken care of by pump 184. The pump 184 is an electronically controlled variable volume pressure compensated positive displacement piston pump such as is available from Parker® (www.parker.com). Pump 184 receives hydraulic fluid via intake flow line/filter 185 and from reservoir 182. As with the embodiment of FIG. 1, a manifold 186 contains various valves 198, 204, 207, 208 that can be internally of manifold 186. Discharge flow line 187 transmits pressurized oil from pump 184 to tees 188, 189. A check valve 190 can be positioned in between the tees 188, 189 in discharge line 187. At internal manifold tee 183, discharge flow line 187 communicates with flow lines 191, 192.

Flow line 192 communicates with accumulator 193. As with the embodiment of FIG. 1, the accumulator 193 has an oil containing portion 194, a gas containing portion 195, and wherein arrow 196 indicates the level of oil 194 contained within accumulator 193.

Flow control valve 197 can be the same as the valve 164 of FIG. 1. The directional valve 198 of FIG. 2 can be the same as the directional valve 165 of FIG. 1.

Hydraulic cylinder 199 provides a cylinder body 200 that includes a pushrod 201 that can be raised or lowered. The pushrod 201 has a rod end 202 that can be coupled to a pumping string such as a plurality of sucker rods 228 connected end to end. Pushrod 201 (and sucker rods 228) rises and falls during operation as illustrated by arrow 18 in FIG. 2.

Flow line 203 connects to flow line 191 at internal manifold tee 210. Flow line 203 communicates with proportional flow control valve 204, oil cooler/fan 205, filter 206 and reservoir 182.

Relief valve 207 is placed in flow line 211 that extends between tee 189 and reservoir 182. The relief valve 207 enables excess pressure to be vented from the discharge flow line 187 via flow line 211 to reservoir 182.

Valve 208 is a fan control valve that controls the flow of hydraulic fluid via flow line 209 to the fan/oil cooler 205. Flow from line 209 discharges into reservoir 182. The embodiment of FIG. 2 operates in much the same fashion as the embodiment of FIG. 1, but for the elimination of bypass valve 174, that function now taken care of by the pump 184.

FIGS. 3-6 show an alternate construction for the hydraulic cylinder and its connection to the well string, pumping string or sucker rod string 228. In FIGS. 3 and 4, hydraulic cylinder 212 provides a cylinder body 213 and a pushrod 214 that moves between upper and lower positions. Pushrod 214 is affixed to piston 237 and travels therewith. At the lower end portion of pushrod 214 is provided female connector 215 to which is connected elongated polished rod 216.

Frame 217 forms an interface between cylinder body 213 and a wellhead tree 220. The frame 217 has an upper end portion 218 to which cylinder body 213 is mounted using its flange 231. The frame 217 has a lower end portion 219 that attaches to the wellhead tree 220.

Flange 231 can be mounted to upper end portion 218 of frame 217. Rod gland 232 is connected to and extends downwardly from flange 231. Head 233 forms an interface between cylinder body 213 and flange 231 as shown. Flushing box 221 is mounted to the lower end portion of gland 232. The flushing box 221 has an influent port 222 and an effluent port 223, enabling a flushing fluid to be pumped from a source to the flushing box interior 239 and then discharged. A continual stream of flushing fluid (for example hydraulic fluid) continuously cleans the polished rod 216 which is attached to the lower end portion of pushrod 214 at female connector 215.

Cylinder body 213 provides an upper port 234 and a lower port 235. The upper port 234 can be a part of cap 236 which is fastened to the upper end portion of cylinder body 213 as shown. FIG. 4 illustrates a condition wherein the piston 237 is being elevated in the direction of arrows 241. Lower port 235 is receiving inflow of hydraulic fluid as indicated schematically by the arrow 240 in FIG. 4. Fluid above piston 237 is evacuated via port 244 illustrated in FIG. 5, the arrows 229 indicate schematically the flow direction of oil as the piston 237, pushrod 214, and polished rod 216 are elevated. Coupling 227 is also elevating as illustrated in FIG. 5.

In FIG. 6, the piston 237 is being lowered. Fluid escapes cylinder 212 via flow line 243 as illustrated by arrow 247 in FIG. 6. Port 244 is simply a vent at the top of the cylinder 212 as indicated by arrow 246 in FIG. 6. String pot 238 is mounted upon cap 236. String pot 238 is a measuring apparatus that is commercially available from Parker (www.parker.com). The String pot 238 has a cable or wire 248 that attaches at 249 to piston 237 or pushrod 214. As the piston 237 raises and lowers, the cable or wire 248 pays out or is retrieved by string pot 238. The string pot 238 is interface with suitable instrumentation with the programmable logic controller or PLC 39. Thus, the string pot 238 replaces the limit switches of FIGS. 1-42.

A flow tee 224 can be mounted upon wellhead tree 220 below frame 217. The flow tee 224 enables oil that is being pumped from the well to be transmitted to tankage via flow line 225 as indicated schematically by arrow 230. Flow line 225 can be a vent line from top of wellhead 220. Blowout preventer 226 can be positioned below flow tee 224. Polished rod 216 can be for example about 25-30 feet in length. Thus, the polished rod enables a very long pump stroke to be provided for pumping oil. Because the polished rod 216 extends through the flushing box 221 and into the wellhead tree 220, coupling 227 can be placed below blowout preventer 226 for connecting the polished rod 216 to sucker rods or pumping string 228. The pumping cylinder arrangement of FIG. 3 enables the frame 217 to be relatively short such as for example about three feet in height.

FIG. 7 shows another alternate embodiment of the apparatus of the present invention, designated generally by the numeral 250. Oil well pump 250 provides a pump (e.g. hydraulic piston pump) 253 that receives hydraulic fluid via a reservoir 251 and intake flow line/filter 252. The hydraulic piston pump 253 is driven by a prime mover (e.g. engine or electric motor). A manifold assembly 254 is shown surrounded by dotted lines in FIG. 7. The manifold assembly 254 includes various flow lines as shown in FIG. 7, directional valve 265, proportional flow control valve 271, relief valve 275, and valves 274, 276. A discharge flow line 255 extends from the discharge side of pump 253 to internal manifold tee 257. Check valve 256 can be placed in discharge flow line 255. Valves 265, 271, 274, 275, 276 can be a part of (e.g. internal) manifold 254.

At internal manifold tee 257, flow lines 258, 259 communicate with discharge flow line 255. The flow line 259 extends through flow control valve 264 and to accumulator 260. The accumulator 260 has an oil containing portion 261 and a gas containing portion 262. In FIG. 7 arrow 263 indicates schematically the level of oil 261 in accumulator 260.

Hydraulic cylinder 266 is connected to both accumulator 260 and pump 253 via flow line 258. Hydraulic cylinder 266 includes a cylinder body 267 and an extendable pushrod 268. The pushrod 268 is movable between retracted upper and extended lower positions. The pushrod 268 provides a rod end 269 that is fitted with a coupling (e.g. coupling 20 of the embodiments of FIGS. 1-42 in Publication No. US 2007/0261841A1, published 15 Nov. 2007, and in Publication No. WO 2007/090193 A2, published 9 Aug. 2007, both of which are hereby incorporated by reference) which connects the pushrod 268 to a well string such as the pumping string 21 (e.g. sucker rods) shown in FIGS. 1-42 in Publication No. US 2007/0261841A1, published 15 Nov. 2007, and in Publication No. WO 2007/090193 A2, published 9 Aug. 2007. Flow line 270 extends from internal manifold tee 277 through proportional flow control valve 271 to reservoir 278. Reservoirs 251, 278 can be a common reservoir. The flow line 270 can be provided with an oil cooler 272 and filter 273. Excess pressure in the system can be relieved using relief valve 275. Valve 276 is a valve that controls flow of fan/cooler 272.

In operation, the prime mover (e.g. engine or electric motor) is started which operates hydraulic pump 253. The hydraulic pump 253 initially rotates at a speed of about 1800 rpm's and is destroked. The hydraulic pump 253 can be a Parker Model P1075XS (01SRM5AEY0T00CPB). A pumping cycle begins by giving the hydraulic piston pump 253 a command using a controller (such as the controller 39 described herein in reference to FIGS. 1-42), stroking it to charge accumulator 260. When accumulator 260 is fully charged, the directional valve 265 is energized, while maintaining the command to the pump 253. Oil 261 is then directed from the charged accumulator 260 through the flow control valve 264 and from the pump 253 into the rod end 268 of the hydraulic cylinder 266. Valve 264 enables free flow in and restricted flow out to control speed of upstroke of cylinder 266. Pushrod 268 will then retract lifting the pumping string until a proximity switch is actuated by a coupling that is mounted on the rod end 269.

The controller 39 then de-energizes the directional valve 265 and activates the proportional control valve 271 forcing it to open until the pushrod 268 begins to fall at a desired velocity. The degree of opening of the proportional control valve 271 controls how fast fluid leaves the cylinder body 267 and flows via flow lines 258, 270 through the proportional flow control valve 271 and into reservoir 278.

Eventually, the coupling on the rod end 269 reaches a second proximity switch which is positioned a short distance (e.g. approximately one foot) from the bottom of the travel of the pushrod 268. When the coupling reaches the second proximity switch, a current signal to the proportional control valve 271 is decreased, forcing the pushrod 268 to decelerate until the coupling 20 on the rod end 269 of the pushrod 268 reaches a third proximity switch. The electrical signal from the controller 39 will then be removed from the proportional control valve 271, with a voltage signal then being sent by controller 39 to the directional valve 265 while maintaining the command to the pump 253 to continue pumping. Oil 261 returning from the cylinder body 267 through the proportional control valve 271 passes through an oil cooler 272 and filter 273 before reaching reservoir 278.

During the time that the pushrod 268 is extending with respect to the cylinder body 267, oil 261 is being pumped by the pump 253 to the accumulator 260, charging the accumulator 260 for use in the next cycle. The accumulator 260 will thus have a pressure change of between about five hundred (500) psi depending on sucker rod string load when it has been discharged by transmitting fluid to the cylinder 266 and a maximum pressure value of about three thousand (3,000) psi depending on sucker rod string load when it is fully charged by the pump 253 during that time that the pushrod 268 is extending and cylinder 266 is draining.

A second, optional, accumulator 279 is shown in FIG. 7, connected to flow line 258 via flow line 283. As with accumulator 260, the accumulator 279 has oil at 280 and gas at 281. The arrow 282 shows the surface of oil 280. Accumulator 279 is used to remove surge or shock in the operation of hydraulic cylinder 266 to help protect cylinder 266. Accumulator 279 is in the discharge line of the pump. Accumulator 279 may have a capacity of, for example, around one quart, while accumulator 260 may have a capacity of around 15 gallons.

Accumulator 260 my be, for example, an integrated accumulator with a capacity of around 15 gallons, or it may be an accumulator with a capacity of around 5 to 7.5 gallons, for example, with a gas bottle having a capacity of around 10 gallons, to give it a total capacity of around 15 to 17.5 gallons, for example.

Also, multiple smaller capacity accumulators 260 could be used instead of one larger capacity accumulator 260 (due to space constraints, for example).

In all accumulators, the oil can be, for example, hydraulic oil such as Exxon Humble Hydraulic H68 brand hydraulic oil or equivalent, biodegradable oil, Sea Blue Hydraulic Oil 68 by Industrial Oils Unlimited of Arkansas; the gas can be, for example, nitrogen, carbon dioxide, or any other preferably non-toxic and non-flammable commercially available compressed inert gas.

Valve 274 is optional, though preferred.

The following is a list of parts and materials suitable for use in the present invention.

PARTS LIST Part Number Description

-   -   150 oil well pump     -   151 reservoir     -   152 intake flow line/filter     -   153 hydraulic piston pump     -   154 manifold assembly     -   155 discharge flow line     -   156 check valve     -   157 internal manifold tee     -   158 flow line     -   159 flow line     -   160 accumulator     -   161 oil     -   162 gas     -   163 arrow     -   164 flow control valve     -   165 directional valve     -   166 hydraulic cylinder     -   167 cylinder body     -   168 pushrod     -   169 rod end     -   170 flow line     -   171 proportional flow control valve     -   172 oil cooler/fan     -   173 filter     -   174 bypass valve     -   175 relief valve     -   176 valve     -   177 internal manifold tee     -   178 reservoir     -   180 oil well pump     -   181 reservoir     -   182 reservoir     -   183 internal manifold tee     -   184 pump     -   185 intake flow line/filter     -   186 manifold     -   187 discharge flow line     -   188 tee     -   189 tee     -   190 check valve     -   191 flow line     -   192 flow line     -   193 accumulator     -   194 oil     -   195 gas     -   196 arrow     -   197 flow control valve     -   198 directional valve     -   199 hydraulic cylinder     -   200 cylinder body     -   201 pushrod     -   202 rod end     -   203 flow line     -   204 proportional flow control valve     -   205 oil cooler/fan     -   206 filter     -   207 relief valve     -   208 valve     -   209 flow line     -   210 tee     -   211 flow line     -   212 hydraulic cylinder     -   213 cylinder body     -   214 pushrod     -   215 female connector     -   216 polished rod     -   217 frame     -   218 upper end portion     -   219 lower end portion     -   220 wellhead tree     -   221 flushing box     -   222 influent     -   223 effluent     -   224 flow tee     -   225 flow line     -   226 blowout preventer     -   227 coupling     -   228 suckerrod     -   229 flow line     -   230 arrow     -   231 flange     -   232 rod gland     -   233 head     -   234 upper port     -   235 lower port     -   236 cap     -   237 piston     -   238 string pot     -   239 interior     -   240 arrow     -   241 arrow     -   242 arrow     -   243 flow line     -   244 flow line     -   245 arrow     -   246 arrow     -   247 arrow     -   250 oil well pump     -   251 reservoir     -   252 intake flow line/filter     -   253 hydraulic piston pump     -   254 manifold assembly     -   255 discharge flow line     -   256 check valve     -   257 internal manifold tee     -   258 flow line     -   259 flow line     -   260 accumulator     -   261 oil     -   262 gas     -   263 arrow     -   264 flow control valve     -   265 directional valve     -   266 hydraulic cylinder     -   267 cylinder body     -   268 pushrod     -   269 rod end     -   270 flow line     -   271 proportional flow control valve     -   272 oil cooler/fan     -   273 filter     -   274 bypass valve     -   275 relief valve     -   276 valve     -   277 internal manifold tee     -   278 reservoir     -   279 accumulator     -   280 oil     -   281 gas     -   282 arrow     -   283 flow line     -   319 flow line

All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise.

The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims. 

1. A hydraulic oil well pumping apparatus, comprising: a) a hydraulic cylinder having a rod that is movable between a upper and lower rod positions; b) a pumping string that extends downwardly from the rod, the string being configured to extend into an oil well for pumping oil from the well; c) a prime mover; d) a hydraulic pump that is powered by the prime mover, said pump having a compensator that regulates pump flow and pump pressure; e) a directional control valve that moves between open flow and closed flow positions; f) a flow line connecting the pump and the hydraulic cylinder, the control valve being positioned in the flow line so that it can control flow between the hydraulic pump and hydraulic cylinder; g) a proportioning valve; h) a hydraulic fluid reservoir for containing hydraulic fluid to be supplied to the hydraulic pump; i) a flow line that transmits hydraulic fluid from the hydraulic cylinder to the reservoir via the proportioning valve; j) an electronic control system that controls movement of the rod as it moves between the upper and lower positions by controlling the control valve and the proportioning valve wherein the control system includes an electrical signal that opens or closes the proportioning valve so that a control of rod movement is enabled when the rod changes direction at the lower position of the rod, and wherein the proportioning valve is choked to lower flow through it as the rod is descending from the upper toward the lower position; and k) an accumulator that enables pressure to be accumulated, the accumulator in fluid communication with the pump and the hydraulic cylinder.
 2. A method of pumping oil from an oil well, comprising the steps of: a) providing a hydraulic cylinder having a rod that is movable between upper and lower rod positions, a pumping string that extends downwardly from the rod, the string being configured to extend into an oil well for pumping oil from the well, a prime mover, a hydraulic pump that is powered by the prime mover, said pump having a compensator that regulates pump flow and pump pressure; b) providing a directional control valve that moves between open flow and closed flow positions; c) connecting the pump and the hydraulic cylinder with a first flow line that transmits hydraulic fluid from the pump to the cylinder, the directional control valve being positioned in the first flow line; d) controlling flow between the hydraulic pump and hydraulic cylinder with the directional control valve; e) providing a proportioning valve, a hydraulic fluid reservoir for containing hydraulic fluid to be supplied to the hydraulic pump, a second flow line that transmits hydraulic fluid from the hydraulic cylinder to the reservoir via the proportioning valve; and f) controlling movement of the rod as it moves between the upper and lower rod positions by controlling the control valve and the proportioning valve with a control system that generates an electrical signal that opens or closes the proportioning valve, enabling control of rod movement when the rod changes direction; and g) choking the proportioning valve to gradually lower the volume of hydraulic fluid flow through it as the rod is descending from the upper toward the lower position.
 3. The method of claim 2 wherein the control system includes at least one proximity switch, and further comprising the step of activating a choking of the proportioning valve at a selected position of the rod relative to the proximity switch.
 4. The method of claim 2 wherein the control system includes a plurality of proximity switches, and further comprising the step of generating a signal when the rod assumes a selected position relative to each of the cylinder.
 5. The method of claim 4 wherein the control system includes an electronic proximity switch and further comprising the step of activating the directional control valve with the proximity switch to move between open flow and closed flow positions.
 6. The method of claim 4 wherein the control system includes a proximity switch and further comprising the step of using the proximity switch to activate the directional control valve to move from an open flow position to a closed flow position when the rod reaches the upper rod position relative to the cylinder.
 7. The method of claim 4 wherein the control system includes a proximity switch and further comprising the step of using the proximity switch to activate the directional control valve to move from a closed flow position to an open flow position when the rod reaches the lower rod position relative to the cylinder.
 8. The method of claim 2 wherein the control system includes a plurality of three proximity switches and further comprising sending an electronic signal with a proximity switch when the rod assumes a selected position relative to each proximity switch.
 9. The method of claim 8 further comprising activating a proximity switch when the rod is at the upper rod position relative to the cylinder.
 10. The method of claim 8 further comprising the step of activating a proximity switch when the rod is at the lower rod position relative to the cylinder.
 11. The method of claim 8 further comprising the step of activating a proximity switch when the rod is at a position that is in between the upper and lower rod positions.
 12. A method of pumping oil from an oil well, comprising the steps of: a) providing a hydraulic cylinder having cylinder body and a piston that is movably mounted to the cylinder to travel between upper and lower piston positions, a pumping string that extends downwardly from the piston, the pumping string being configured to extend into an oil well and including one or more sucker rods for pumping oil from the well, a prime mover and a hydraulic pump that is powered by the prime mover; b) providing a directional control valve that moves between open flow and closed flow positions and a first flow line connecting the pump and the hydraulic cylinder, the directional control valve being positioned to valve flow in the first flow line; c) controlling the flow of hydraulic fluid between the hydraulic pump and hydraulic cylinder with the directional control valve; d) providing a proportioning valve and a hydraulic fluid reservoir for containing hydraulic fluid to be supplied to the hydraulic pump; e) transmitting hydraulic fluid from the hydraulic cylinder to the reservoir via the proportioning valve in a second flow line; and f) controlling movement of the piston as it moves between the upper and lower piston positions by controlling the directional control valve and the proportioning valve, wherein a control system generates a signal that opens or closes the proportioning valve a selected variable amount so that a control of the speed of piston movement is enabled when the rod changes direction at the lower position of the piston; and g) gradually choking the proportioning valve to lower the volume flow through it as the piston is descending from the upper toward the lower position.
 13. The method of claim 12 wherein the control system includes at least one proximity switch that is positioned next to the hydraulic cylinder and further comprising the step of the proximity switch initiating a choking of the proportioning valve at a selected position of the piston relative to the cylinder.
 14. The method of claim 12 wherein the electronic control system includes a plurality of proximity switches and further comprising the step of a proximity switch sending a signal when the piston assumes a selected position relative to the cylinder.
 15. The method of claim 14 wherein the control system includes a proximity switch and further comprising activating the directional control valve with a proximity switch to move between open flow and closed flow positions.
 16. The method of claim 14 wherein the control system includes a proximity switch and further comprising the step of activating the directional control valve to move from an open flow position to a closed flow position when the piston reaches an upper piston position.
 17. The method of claim 14 wherein the control system includes a proximity switch and further comprising the step of activating the directional control valve to move from a closed flow position to an open flow position when the piston reaches a lower piston position.
 18. The method of claim 12 wherein the electronic control system includes a plurality of three proximity switches and further comprising the step of sending a signal with a proximity switch when the piston assumes a selected position relative to each proximity switch.
 19. The method of claim 18 further comprising the step of activating a proximity switch when the rod is at the upper piston position relative to the cylinder.
 20. The method of claim 18 further comprising the step of activating a proximity switch when the rod is at the lower piston position relative to the cylinder. 21-71. (canceled) 